We recently upgraded to ArcGIS Desktop 10.5.  Everything looked fine until we noticed all our locators we use for geocoding had disappeared from our enterprise geodatabase!  Someone deleted the locators?  Luckily we still had an older version of Desktop and checked the enterprise geodatabase, and they were all there.  What?  Then we tried to add a new locator to the geodatabase using 10.5 and the option was gone!

As it turns out, ESRI has decided at 10.5 that you can no longer create or use locators in geodatabases, including enterprise geodatabases.  This means that prior to 10.5 address locators are visible inside of the geodatabase, but after installing 10.5 locators are no longer visible when viewing the contents of the geodatabase. In ArcGIS Pro 1.4 as well, address locators can no longer be seen inside of geodatabases to be able to use them as inputs into tools.

So now what?  You must copy or move your address locators from geodatabases into file folders before installing 10.5, using copy/paste in ArcCatalog or running the Data Management Copy tool.  You read that correctly!  Locators must be in a file folder now, like you do with your shapefiles.  Make sure to do this before you upgrade to 10.5!  And if you want to give your users access to the locators, I guess you would have to place them on a network drive.  Maybe you do that with other files already, so it won’t be a big deal for you.

Also if you use locators for a geocoding service in ArcGIS Server, they will fail in Server 10.5.  They must be moved to file folders and used from there.

More info about this here.